I'm thinking this setting should be called "congestion_action" with one of a few options: 1) wait, 2) drop, 3) trim

Waiting would do what exists today. Dropping would simply discard the event. Trim would do what you have implemented today.

Thoughts? Basically, "congestion_keep_recent" is a very specific thing that we could generalize to be more explicit in name and purpose, as proposed above ;)